Here's a method that tells you right where your version of SketchUp is looking for extensions. Copy and paste the code into the Window > Ruby Console dialog, and press ENTER. It works for all versions of SketchUp, and on all operating systems, too.

(1) make a checklist of all the Tutorials, and go thru them 1 by 1, and check them off the list as you do.

(2) make a checklist of all the free downloadable books, and down load them one by one. Put them in a folder on your Desktop (or wherever you can find them easily.) And read them.

(3) For Standard ruby Reference, get the CHM for Ruby here, put it in this same folder.

Get comfortable with Standard Ruby. When your ready to script for Sketchup:

(4) On the Reference list (link above,) go to the Sketchup Specific section, and download Alex's Cheatsheet, and bookmark the Sketchup API Documentation website. (You'll be referencing it a lot.) It has the methods for the modules and classes for 'talking' to Sketchup, and manipulating it's models.

(5) Go through all the available Sketchup Ruby tutorials (on the list.)

(6) Read the code examples in your plugins/Examples folder.

(7) Have fun. Start fooling around with Ruby under Sketchup. Usually the best thing is to start by customizing the examples.

(8) Whenever you have questions, come back to this forum, and first do a search (it's likely your question has already been asked.) If not.. start a new topic (make the the topic title simple but informative... a shortened version of your question. Don't make it "Help Me!", that does not work well.)

(9) Before going into advanced Sketchup scripting, download more advanced plugins from the plugins forum (or other websites.. see the Resource list,) and examine them. See how they did things. This the best way to learn how to do things right. If you have a question about why an author did something a certain way... you can either Private Message them, or see if there is a discussion topic specific to their plugin, here in the Developer's forum, and post a question at the end of that topic. If no topic exists, create one by putting the plugin name in square brackets following by 'coding questions.' Please don't ask coding questions in the Plugin distribution topic of the Plugins forum. Ask them here in the Developers forum.

In his main post above, Dan basically suggests becoming very familiar with Ruby before beginning to use it with Sketchup. And he has a very good point, especially when it comes to the powerful and rather esoteric ways that Dan himself can use Ruby.

However, in the other direction, the Bastard's Book above, http://ruby.bastardsbook.com/, makes the point that "Programming and knitting are both skills that require continual practice but aren't easily improved by doing things other than, well, actually programming or knitting." So he presents lots of simple ways to get in your practice. "The good thing about programming compared to knitting a scarf is that you can experiment and mess up all you want without having to go out and buy more yarn."

Even further in that direction, Matthew Scarpino's book, "Automatic Sketchup", gives you ways to get that fundamental practice by working in Sketchup. And that's your goal, isn't it? I would even recommend Matt's book and SketchUp Ruby for initial programming instruction -- the instant gratification of creating SU objects is hard to beat.